This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A111986 #4 Mar 30 2012 17:22:41
%S A111986 1,3,2,5,0,5,2,6,2,1,2,12,0,4,1,6,0,6,1,3,4,7,1,17,0,0,3,7,0,6,2,6,3,
%T A111986 1,0,15,1,3,0,6,0,11,0,14,3,1,0,24,2,0,1,1,1,10,1,8,3,0,0,13,0,5,5,7,
%U A111986 0,10,0,3,2,3,0,26,0,3,1,6,4,0,2,9,3,1,0,25,0,0,2,18,0,13,1,3,4,0,0,26
%N A111986 Number of numbers having n quadratic residues.
%e A111986 a(4)=5 because the numbers 6, 7, 9, 12 and 16 each have 4 quadratic residues.
%t A111986 t=Table[Length[Union[Mod[Range[0, n/2]^2, n]]], {n, 10000}]; Table[Length[Position[t, n]], {n, 100}]
%Y A111986 Cf. A037041 (n such that a(n)>0), A037046 (n such that a(n)=0), A111987 (least number having n quadratic residues), A111988 (greatest number having n quadratic residues).
%K A111986 nonn
%O A111986 1,2
%A A111986 _T. D. Noe_, Aug 25 2005